TY - BOOK AU - Fida Banu, M R AU - Rani, B (Guide) TI - Organic and inorganic amendments for surface and subsoil acidity amelioration in southern laterites of Kerala U1 - 631.4 PY - 2024/// CY - Vellayani PB - Department of Soil Science and Agricultural Chemistry, College of Agriculture KW - Soil Science KW - Agricultural Chemistry KW - Organic and inorganic amendments KW - Subsoil acidity KW - Southern laterites N1 - MSc N2 - The study entitled Organic and inorganic amendments for surface and subsoil acidity amelioration in southern laterites of Kerala was conducted in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani during 2021-2023 with the objectives to evaluate various organic amendments and liming materials for amelioration of surface and subsoil acidity in the southern laterite soils (AEU -8) of Kerala and assessment of the effect on crop production using tomato as test crop. The experiment comprised of two parts viz. column incubation experiment and field validation of amendments for soil acidity. A column incubation study was conducted under laboratory conditions for 12 weeks using the southern laterite soils (AEU-8) of College of Agriculture, Vellayani, to elucidate the acid neutralization capacity of organic and inorganic amendments applied to the soil and to monitor the amelioration of surface and sub soil acidity. Soil samples were collected to a depth of 60 cm from the experiment site and filled in polyvinyl chloride (PVC) tubes of 10 cm diameter and 60 cm length and with facility to collect the leachate in such a manner as to attain the same bulk density as that of the field. Treatments were applied to the top 15 cm soil on weight basis and thoroughly mixed. The soil columns were maintained at field capacity. There were 17 treatments which included farmyard manure (FYM) @ 20 t ha-1 , humic acid (HA) @ 10 kg ha-1 , poultry manure (PM) @ 1 t ha-1 and coconut frond biochar (CFB) @ 10 t ha-1 along with lime or dolomite or calcium silicate (CS) or phosphogypsum (PG) at lime requirement (LR) and soil alone. Biochar produced from coconut frond by the process of slow pyrolysis and other organic amendments, were analysed for various physical and chemical properties using standard procedures. Humic acid recorded the highest bulk density (0.51 Mg m-3 ) while the lowest was for CFB (0.36 Mg m-3 ). The highest pH was for CFB (10.70) followed by HA (9.84). The TOC (41.11%), P (0.95%), K (0.91%), Ca (0.56%), Mg (0.45%), S (0.25%) and B (6.28%) were highest for CFB while the highest value of N (2.97%) was for PM. Fe (813.30 mg kg-1 ), Mn (94.50 mg kg-1 ), Zn (40.12 mg kg-1 ) and Cu (5.13 mg kg-1 ) were highest for FYM. CCE of lime, dolomite, PG and CS were 123.5%, 124 %, 58.1% and 58.06% respectively. The highest concentration of total Ca was observed for lime (37.10%) and for total Mg, was for dolomite (16.03%). Three leching events were performed in the prepared soil columns at 4, 8 and 12 weeks of incubation by adding double the pore volume of water. Leachate was acidic in pH for all the treatments and showed an increase up to 12th week of incubation. The EC, total OC, P, K, Ca, S, Mg and B contents in the leachate decreased from the 4 th week to 12th week. Total N content showed a general decrease from the 4 th week to 8th week and an increase at 12 weeks except for the treatment supplied with CFB along with either lime, dolomite, PG or CS which showed a gradual increase. The cumulative contents of total Fe, Mn, Zn and Cu were significantly highest for the control treatment. pH of leached soils showed significant increase at all depths after the incubation period compared to control and it decreased as depth increased from 0-15 cm to 30-60. CFB @ 10 t ha-1 with lime as per LR showed the highest value for pH at 0-15 cm depth of soil and it was on par with PM @ 1 t ha-1 with lime as per LR and CFB @ 10 t ha-1 with CS as per LR. Significantly highest pH was noticed for FYM @ 20 t ha-1 with CS as per LR at 15-30 cm depth of soil. At 30-60 cm depth of soil significantly highest value for soil pH was observed for CFB @ 10 t ha-1 with PG as per LR. Significantly lower mean values for exchangeable Al3+ and H+ at different depths were observed for the treatment combination CFB @ 10 t ha-1 with CS as per LR. The exchangeable Ca content increased significantly at all depths of soil compared to the control. The higher mean values for exchangeable Ca were recorded by CFB @ 10 t ha-1 with CS as per LR treatment at 0-15, 15-30 and 30-60 cm depths of soil. Significantly highest value for exchangeable Mg was recorded by the treatment supplied with CFB @ 10 t ha-1 with dolomite as per LR at all the depths of soil. Available N was significantly higher for the treatment receiving PM @ 1 t ha-1 with lime as per LR which was on par with dolomite or PG or CS as per LR and with FYM @ 20 t ha-1 + PG as per LR. Available P showed the maximum value for treatment supplied with FYM @ 20 t ha-1 + CS as per LR which was on par with CFB @ 10 t ha-1 with CS as per LR. The treatments receiving CFB @ 10 t ha-1 with lime as per LR gave the maximum value which was on par with CS or PG or dolomite as per LR. The available S content was highest for CFB @ 10 t ha-1 with PG as per which was on par with all the treatments receiving PG as per LR with FYM @ 20 t ha-1 or HA @ 10 kg ha-1 or PM @ 1 t ha-1 . Available Fe, Mn, Zn and Cu were recorded highest for the control treatment. Based on the acidity amelioration ability, best five treatments from the column incubation experiment viz. CFB @ 10 t ha-1 with dolomite as per LR, FYM @ 20 t ha-1 with PG as per LR, FYM @ 20 t ha-1 with CS as per LR, HA @ 10 kg ha-1 with CS as per LR and CFB @ 10 t ha-1 with CS per LR each along with NPK as per POP were selected for field validation using tomato as the test crop including KAU POP, KAU organic POP and absolute control. The physical properties of soil such as bulk density, porosity, water holding capacity and aggregate stability were significantly improved by the application of CFB @ 10 t ha-1 along with CS or dolomite as per LR, compared to other treatments. The surface and subsoil acidity were significantly reduced by the application of treatments compared to the control. Treatments receiving CFB @ 10 t ha-1 with dolomite or CS as per LR showed significant improvement for pH, exchangeable Al3+ and H+ , and exchangeable Ca and Mg compared to other treatment combinations. CFB@ 10 t ha-1 with CS as per LR recorded the highest value for available OC, N, K and B and it was on par with CFB @ 10 t ha -1 with dolomite as per LR. FYM @ 20 t ha-1 with PG as per LR showed highest value for available P and S which was on par with the treatment receiving CFB @ 10 t ha-1 with dolomite or CS as per LR. Plant height, number of branches per plant, root length and volume, fresh weight of shoot and root, dry matter production, number of fruits per plant and yield were highest for the treatment receiving CFB @ 10 t ha-1 with CS as per LR which was on par with CFB@ 10 t ha-1 with dolomite as per LR. The higher mean values for uptake of N, P, K, Ca, S and B by tomato was for CFB @ 10 t ha-1 with CS as per LR. Significantly higher mean values for uptake of Mg, Mn and Zn by tomato was significantly higher for CFB@ 10 t ha-1 with dolomite as per LR, while FYM @ 20 t ha-1 with CS as per LR showed the highest improvement for total uptake of Fe and Cu by tomato. The quality parameters of tomato fruit such as vitamin C and lycopene content were significantly improved by the application of treatments and the higher mean values was observed for FYM @ 20 t ha-1 with PG as per LR and CFB @ 10 t ha1 with CS as per LR, respectively. It may be inferred that there was significant movement of exchangeable calcium and magnesium through the depth in all treatments. Exchangeable H+ and Al3+ were significantly reduced by the combined application of organic and inorganic amendments. The highest acidity amelioration capacity in both incubation and field study was recorded by CFB @ 10 t ha-1 with CS as per LR. The treatment combinations CFB @ 10 t ha-1 with dolomite or CS as per LR, FYM @ 20 t ha-1 with CS or PG as per LR, and HA @ 10 kg ha-1 with CS as per LR were superior to other treatment combinations in reducing pH, exchangeable Al3+, and H+ and improving exchangeable Ca and Mg of the soil during the incubation study. Application of CFB @ 10 t ha-1 with dolomite or CS as per LR showed the highest reduction in acidity parameters and improved the content and uptake of nutrients during the field study. Application of CFB @ 10 t ha-1 with dolomite or CS as per LR and NPK as per POP increased the fruit yield by 26 % and 37 % compared to KAU POP. From the study, it can be concluded that CFB @ 10 t ha-1 along with dolomite as per LR is the economically viable and best treatment for amelioration of surface and subsoil acidity ER -